A research group from Chalmers
University of Technology, Sweden, have made rapid progress towards the
development of a molecule which can store solar energy for later use. They have
designed, what is called, Molecular Solar Thermal Energy Storage (MOST). The
results are published in the journal Energy & Environmental Science.

The
energy system MOST works in a circular manner. First, the liquid captures
energy from sunlight, in a solar thermal collector on the roof of a building.
Then it is stored at room temperature, leading to minimal energy losses. When
the energy is needed, it can be drawn through the catalyst so that the liquid
heats up. The hot liquids are used in the domestic heating systems, and later
it can be sent back up to the roof to collect more energy. It defines a system completely
free of emissions, and without damaging the molecules.

The molecule is made from carbon,
hydrogen and nitrogen and has the unique property that when it is hit by
sunlight, it is transformed into an energy-rich isomer -- a molecule which
consists of the same atoms, but bound together in a different way. This isomer
can then be stored for use when that energy is later needed -- for example, at
night or in winter.

"The energy in this isomer can now
be stored for up to 18 years. And when we come to extract the energy and use
it, we get a warmth increase which is greater than we dared hope for,"
says the leader of the research team, Kasper Moth-Poulsen, Professor at the
Department of Chemistry and Chemical Engineering.

The research group has also developed a
catalyst for controlling the release of the stored energy, which acts as a
filter, through which the liquid flows, creating a reaction which warms the
liquid by 63 degrees Celsius. If the liquid has a temperature of 20C when it
pumps through the filter, it comes out the other side at 83 degrees Celsius. At
the same time, it returns the molecule to its original form, so that it can be
then reused in the warming system.

Researchers hope that the technology
could be in commercial use within 10 years.